Where can I get a new battery for my daughters Kocaso MX736?

My daughter has had many issues battery I guess crapped out. She tried to turn it on and it she plugged it in to charge over night and nothing. Battery only last for a half hour when it was on. This was given to her by my sister and she never used it. Is there a replacement battery and if so how where can I get one and how do I replace it?

Welcome to Android Central! It could be a problem with the battery, the charger, the charge port, or the motherboard. Try using a different charging cable and wall charging plug, and let it sit on a wall outlet for at least 4-5 hours. If that still doesn't help, then you'd have to contact Kocaso: Welcome to KOCASO